Some internal combustion (IC) engines, such as those used in motor vehicles, employ selective deactivation of valves for specific engine cylinder(s), often called active fuel management, in order to reduce the engine's fuel consumption when full engine power and torque are not required.
Under extreme operating conditions, and as a by-product of power generation, IC engines typically generate elevated amounts of heat energy within their combustion chambers. Such heat energy may in turn cause significant thermal stresses. In order to reduce such thermal stresses, IC engines are generally cooled in order to maintain their operating temperature in a particular range and ensure the engine's efficient and reliable performance. In a majority of motor vehicles, IC engines are cooled by a circulating fluid, such as a specially formulated chemical compound mixed with water. Additionally, such engines are lubricated and cooled by oils that are generally derived from petroleum-based and non-petroleum synthesized chemical compounds.
The generated heat energy usually affects the entire engine structure, but is initially absorbed by the engine's pistons. Accordingly, for enhanced durability, IC engines, such as those equipped with active fuel management, may additionally employ piston squirters or oil jets to cool the pistons and permit the engine to reliably withstand elevated thermal stresses.